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Full Discussion: Running process in the background
Top Forums UNIX for Beginners Questions & Answers Running process in the background Post 303015677 by uniran on Tuesday 10th of April 2018 06:28:01 AM
Old 04-10-2018
Running process in the background
Hi,

I have this simple c program that creates duplicate process with fork():

Code:
#include <sys/types.h>
main()
{
if (fork() == 0)
while(1);
else
while(1);
}

I tried running it in the background

Code:
gcc -o test first.c
test &

And I got this list of running process:

Code:
ps -l
F S   UID    PID   PPID  C PRI  NI ADDR SZ WCHAN  TTY          TIME CMD
0 S  1000  46202  46194  0  80   0 -  5782 wait   pts/0    00:00:01 bash
0 T  1000  47701  46202  0  80   0 -  1998 signal pts/0    00:00:00 awk
0 T  1000  47702  46202  0  80   0 -  1998 signal pts/0    00:00:00 awk
0 R  1000  54295  46202  0  80   0 -  8370 -      pts/0    00:00:00 ps
[3]   Exit 1                  test

Why can`t I see the PID of the two process (father and son) created with the fork() ?
 

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LEARN ABOUT BSD

fork

FORK(3F)																  FORK(3F)

NAME

       fork - create a copy of this process

SYNOPSIS

       integer function fork()

DESCRIPTION

       Fork  creates  a  copy  of  the	calling  process.   The only distinction between the 2 processes is that the value returned to one of them
       (referred to as the `parent' process) will be the process id of the copy.  The copy is usually referred to as  the  `child'  process.   The
       value returned to the `child' process will be zero.

       All logical units open for writing are flushed before the fork to avoid duplication of the contents of I/O buffers in the external file(s).

       If the returned value is negative, it indicates an error and will be the negation of the system error code.  See perror(3F).

       A corresponding exec routine has not been provided because there is no satisfactory way to retain open logical units across the exec.  How-
       ever, the usual function of fork/exec can be performed using system(3F).

FILES

       /usr/lib/libU77.a

SEE ALSO

       fork(2), wait(3F), kill(3F), system(3F), perror(3F)

4.2 Berkeley Distribution					   May 27, 1986 							  FORK(3F)
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